JP2000196940A - Video camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a video camera which has a small size and superior characteristics and imparts a feeling that videos and audios are united in one body through zooming by changing the volumes and frequency characteristics of sounds in accordance with the variation of the zoom ratio of a lens by means of one zoom microphone used for various kinds of electric apparatuses by solving the method for changing the directivity of the microphone. SOLUTION: A second filter 14 cuts off the low-frequency portion of the output signal of a first amplifier 13 and a second amplifier 15 amplifies the output signal of the amplifier 13. The output signals of the amplifiers 13 and 15 are inputted to first and second electronic variable resistors 16 and 17. Such a feeling that videos and audios are united in one body is obtained when a control signal voltage generating circuit 18 controls the output signals of the amplifiers 13 and 15 in accordance with the zoom ratio of a lens and adds the output signals of the electronic variable resistors 16 and 17 to each other through zooming operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom microphone mounted on a camera having a function of zooming an image and picking up a zoom sound in synchronism with the image, and a video camera including the same.

[0002]

2. Description of the Related Art In recent years, consumer video cameras have become remarkably popular.

[0003] While most of these consumer video cameras have a zoom function, these built-in microphones have a fixed directivity, and thus have a poor sense of unity of video and audio.

[0004] A video camera equipped with a conventional microphone will be described below. 2. Description of the Related Art Conventionally, a video camera described in JP-A-1-321780 is known. The video camera is shown in FIG. FIG. 3 shows a block diagram of a conventional video camera. In FIG. 3, reference numeral 1 denotes an imaging unit having a zoom function and capable of capturing an image of a subject. Reference numeral 2 denotes a first microphone having a wide directivity used at the time of wide-angle shooting, and is also called an omnidirectional microphone. Reference numeral 3 denotes a second microphone having a narrow directivity used at the time of telephoto shooting, and is also called a unidirectional microphone. Reference numeral 4 denotes a mixer for changing the audio output signal levels of the first and second microphones 2 and 3. Ra,
Rb is a variable resistor provided in the mixer 4. Reference numeral 5 denotes a control signal voltage generation circuit that generates a control signal according to the zooming operation of the imaging unit 1 and controls the mixer 4. Reference numeral 6 denotes a voice recording circuit.

The operation of the conventional video camera configured as described above will be described below.

First, a zoom operation causes a zoom position information signal from the imaging section 1 to be transmitted to a control signal voltage generation circuit 5.
And controls the variable resistors Ra and Rb of the mixer 4 at a zoom ratio corresponding to the zoom position.

For example, when the image pickup section 1 is performing wide-angle photographing, the control signal voltage generation circuit 5 controls to increase the resistance value of the variable resistor Rb of the mixer 4 so as to obtain a narrow directivity at the time of telephoto photographing. The variable resistor Ra of the mixer 4 is controlled so that the sound output signal of the second microphone 3 is attenuated and only the sound output signal of the first microphone 2 having a wide directivity is output to the sound recording circuit 6.

When the image pickup section 1 is performing telephoto shooting, the control signal voltage generation circuit 5 controls to increase the resistance value of the variable resistor Ra of the mixer 4, and outputs the audio output signal of the first microphone 2. And the variable resistor Rb of the mixer 4 is controlled so that only the audio output signal of the second microphone 3 is output to the audio recording circuit 6.

The audio signal controlled as described above is input to the audio recording circuit 6, and the audio signal is recorded on a recording medium or the like.

FIG. 4 shows a change in directivity of an audio signal input to the audio recording circuit 6 in which the variable resistors Ra and Rb of the mixer 4 are controlled at a zoom ratio corresponding to a zoom position.

[0011]

However, in the above-mentioned conventional configuration, since a plurality of microphone units having different directivities are required, the video camera cannot be downsized.
Further, there is a problem that the cost is increased.

An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide a video camera capable of realizing a reduction in size and cost of the video camera.

[0013]

In order to achieve the above object, a video camera according to the present invention comprises an imaging means capable of performing a zoom operation, and controls a sound signal in accordance with the zoom operation of the imaging means. A microphone that picks up sound, a first filter that reduces the low frequency of the audio output signal from the microphone, and a second filter that reduces the low frequency of the audio output signal from the first filter. First level varying means for varying the level of the audio output signal from the first filter, second level varying means for varying the level of the audio output signal from the second filter, and the imaging means In response to the zoom operation in the first
Control means for controlling the levels of the first and second level variable means, and addition means for adding the output audio signals of the first and second level variable means.

With this configuration, the video camera can be downsized by changing the gain and frequency characteristics of the audio output signal of the microphone unit without changing the directivity.
A video camera can be provided at a low price.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claims 1 and 2 of the present invention is a video camera comprising an imaging means capable of performing a zoom operation and controlling an audio signal in accordance with the zoom operation of the imaging means. A microphone that picks up sound, a first filter that reduces a low frequency of an audio output signal from the microphone, a second filter that reduces a low frequency of an audio output signal from the first filter, First level varying means for varying the level of the audio output signal from the first filter, second level varying means for varying the level of the audio output signal from the second filter, and zoom in the imaging means Control means for controlling the levels of the first and second level varying means in accordance with the operation; and adding means for adding the output audio signals of the first and second level varying means. The Do arrangement, since the microphone requires only one, it becomes possible to reduce costs, a video camera capable of miniaturization is obtained.

(Embodiment 1) FIG. 1 is a block diagram of a video camera according to an embodiment of the present invention.
Numeral 11 denotes an omnidirectional microphone which is composed of one microphone. Reference numeral 12 denotes a first filter that cuts a low band of an audio output signal from the microphone 11, 13 denotes a first amplifier that amplifies an audio output signal of the first filter 12, 14
Is a second filter that cuts the low band of the audio output signal from the first amplifier 13, and is 3 dB at a low band of 600 Hz.
It has the characteristic that the level is attenuated. 15 is a second amplifier for amplifying the audio output signal of the second filter 14, 1
Reference numeral 6 denotes a first electronic volume which is a first level variable means for changing the level of the audio output signal from the first amplifier 13, and 17 denotes a second level for changing the level of the audio output signal from the second amplifier 15. A second electronic volume 18 as a variable means is a control signal voltage generating circuit which is a control means for generating a control signal according to a zooming operation of the imaging unit 20 and controlling the first and second electronic volumes 16 and 17. , 19 is an adder which is an adding means for adding the audio output signals of the first and second electronic volumes 16 and 17, 20 is an imaging section which is an imaging means having a zoom function and capable of taking an image of a subject, 21 Is an audio recording circuit for recording the audio signal output from the adder 19 on a recording medium or the like.

FIG. 2 is a characteristic diagram showing the characteristics of the output level with respect to the frequency of the audio signal in the present embodiment.
Is the characteristic of the output signal of the second amplifier 15, and 22 is the characteristic of the output signal of the first amplifier 13.

The operation of the video camera according to the present embodiment configured as described above will be described with reference to FIG.

As for the control of the audio signal in wide-angle shooting, the sound collected by an omnidirectional microphone may be used as it is, but the audio signal in telephoto shooting reduces the low frequency of the audio signal in wide-angle shooting. Thus, sound can be collected by reducing the sound near the microphone.

First, the noise component is removed by cutting the low frequency band of the audio output signal from the omnidirectional microphone 11 with the first filter 12. The audio signal output from the first filter 12 is input to a first amplifier 13 and the first amplifier 13 amplifies the audio output signal. Here, the audio signal output from the first amplifier 13 is called “for wide-angle shooting” and has a characteristic as shown at 22 in FIG. The audio output signal for wide-angle shooting is transmitted to the first electronic volume 1
6 and the second filter 14. The second filter 14 further cuts the low frequency band based on the characteristic that the 3 dB drop in the low frequency band is 600 Hz, and amplifies the audio output signal by 9 to 12 dB by the second amplifier 15. This audio output signal is called "for telephoto shooting" and has a characteristic as shown in FIG. The sound output signal for wide-angle shooting and the sound output signal for telephoto shooting are first and second electronic volumes 16 and 17.
Is input to

On the other hand, when the imaging unit 20 performs a zoom operation,
The control signal voltage generation circuit 18 reads the zoom position information signal from the imaging unit 20, and outputs the audio output signal for wide-angle shooting and the audio output for telephoto shooting to the first and second electronic volumes 16 and 17 according to the zoom ratio. Control the signal.

For example, at the time of wide-angle shooting, the control signal voltage generation circuit 18 controls the first electronic volume 16 so as to pass the audio output signal for wide-angle shooting, and attenuates the audio output signal for telephoto shooting. The second electronic volume 17 is controlled. Further, at the time of telephoto shooting, the control signal voltage generation circuit 18 controls the second electronic volume 17 so as to pass the audio output signal for telephoto shooting, and the first so as to attenuate the audio output signal for wide-angle shooting. The electronic volume 16 is controlled.

Then, the first and second electronic volumes 1
The audio output signals 6 and 17 are added by the adder 19 and output to the audio recording circuit 21. In the audio recording circuit 21,
An audio signal is recorded on a recording medium such as a magnetic tape.

As described above, according to the present embodiment, the output of the audio output signal for telephoto shooting is increased by 8 to 12 dB with respect to the audio output signal for wide-angle shooting, and the wide-angle shooting as shown in the frequency characteristic of FIG. The first filter 12 for zooming and the second filter 14 for telephoto shooting have characteristics, so that when the zoom is operated for telephoto shooting, the low frequency range of the frequency characteristic is cut off.
Since the volume is increased by 8 to 12 dB, the sense of clarity with respect to ambient noise is improved, and an effect of zooming up a distant sound can be obtained. That is, the volume and the surrounding sound of the subject change in accordance with the zoom of the image, and a sufficient sense of unity between the image and the sound can be obtained without changing the directivity.

[0025]

As described above, according to the present invention, even if the directivity is not changed by using two microphone units having different directivities, it is possible to adjust the zoom magnification of the lens with one microphone unit. By changing the audio output level and the frequency characteristic, the volume and the surrounding sound of the subject change in accordance with the zoom of the image, and an excellent effect of obtaining a sufficient sense of unity between the image and the sound can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram of a video camera according to an embodiment of the present invention.

FIG. 2 is a frequency characteristic diagram for explaining the operation of the video camera according to the first embodiment;

FIG. 3 is a block diagram showing a configuration of a conventional video camera.

FIG. 4 is a characteristic diagram showing directional characteristics of a microphone in a conventional video camera.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Microphone 12 1st filter 13 1st amplifier 14 2nd filter 15 2nd amplifier 16 1st electronic volume 17 2nd electronic volume 18 Control signal voltage generation circuit 19 Adder 20 Imaging part

Claims (2)

[Claims] 1. A video camera that includes an imaging unit capable of performing a zoom operation, and controls an audio signal in accordance with the zoom operation of the imaging unit, comprising: a microphone that collects audio; and a microphone that outputs an audio output signal from the microphone. A first filter for reducing the low frequency band, a second filter for reducing the low frequency band of the audio output signal from the first filter, and a first filter for varying the level of the audio output signal from the first filter. Level varying means, second level varying means for varying the level of the audio output signal from the second filter, and levels of the first and second level varying means in accordance with a zoom operation in the imaging means. Control means for controlling the first
And a summing means for summing an output audio signal of the second level varying means. 2. A video camera comprising an imaging unit capable of performing a zoom operation and controlling an audio signal in accordance with the zoom operation of the imaging unit, comprising: a microphone that collects audio, and an audio output signal from the microphone. A first filter for reducing the low frequency band, a second filter for reducing the low frequency band of the audio output signal from the first filter, and a first filter for varying the level of the audio output signal from the first filter. Level varying means, second level varying means for varying the level of the audio output signal from the second filter, and levels of the first and second level varying means in accordance with a zoom operation in the imaging means. Control means for controlling the first
And adding means for adding the output audio signal of the second level variable means, wherein the control means controls to increase the level in the second level variable means when the imaging means is in a telephoto shooting state, A video camera wherein the level of the first level varying means is controlled to be higher when the imaging means is in a wide-angle shooting state.